Method and apparatus for printing three-dimensional structures with image information

ABSTRACT

A method and system for printing 3D structures using 2D monochromatic images (for example, greyscale images) is provided. The method can include instructing a printing device to print a 2D monochromatic image using print material in a reservoir known to contain a structural print material. Greater amounts of print material are printed in locations corresponding to relatively darker regions of the 2D monochromatic image.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/609,220 filed May 31, 2017, now U.S. Pat. No. 10,518,474, whichclaims the benefit of U.S. Provisional Patent Application No. 62/343,686filed May 31, 2016, both of which are incorporated herein by referencein their entirety.

BACKGROUND

The present embodiments relate generally to printing systems, includingthree-dimensional printing systems and methods.

Printing systems can be used to print 2D structures or layers of ink aswell as 3D structures formed from various kinds of 3D printingmaterials. Three-dimensional printing systems and methods may beassociated with various technologies including fused deposition modeling(FDM), electron beam freeform fabrication (EBF), selective lasersintering (SLS) as well as other kinds of three-dimensional printingtechnologies.

Structures formed from three-dimensional printing systems can be usedwith objects formed by other manufacturing techniques. These includetextile materials used in various articles of footwear and/or articlesof apparel.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments can be better understood with reference to the followingdrawings and description. The components in the figures are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the embodiments. Moreover, in the figures, likereference numerals designate corresponding parts throughout thedifferent views.

FIG. 1 is a schematic view of an embodiment of a printing systemincluding a printing device and a computing system;

FIG. 2 is a schematic view of an embodiment of inputs and outputs to aprinting system;

FIG. 3 is a schematic view of an embodiment of some subcomponents of aprinting system;

FIG. 4 is a schematic view of an embodiment of a printhead for aprinting system;

FIG. 5 is a schematic view of a relationship between a shade level of apixel in a greyscale image and the height for a corresponding printedregion;

FIG. 6 is an embodiment of a process for a printing system;

FIG. 7 is a schematic view of an embodiment of a printing system thatshows a possible set of printing instructions delivered to a printingdevice from a processing system;

FIG. 8 is a schematic view of another embodiment of a printing systemincluding various input images;

FIG. 9 is a schematic view of an embodiment of some components of aprinting system;

FIG. 10 is a schematic view of a process of controlling a printingdevice;

FIG. 11 is a schematic view of an embodiment of file information thatcould be provided to a printing system;

FIG. 12 is a schematic view of a method of printing regions of differentheights, according to an embodiment;

FIG. 13 is an embodiment of a process of printing regions of differentheights, according to an embodiment;

FIG. 14 is a schematic view of another method of printing regions ofdifferent heights, according to an embodiment;

FIG. 15 is a schematic view of a process of printing regions ofdifferent heights, according to an embodiment;

FIG. 16 is a schematic view of a table showing a relationship betweenspot color percentage and print layer thickness, according to anembodiment;

FIG. 17 is a schematic view of a set of layers printed using a set ofspot color percentages, according to an embodiment;

FIG. 18 is a schematic view of a set of layers printed using a set ofspot color percentages, according to an embodiment;

FIG. 19 is a schematic view of a process for generating and using acorrected spot color table for printing; and

FIG. 20 is a schematic view of a table showing adjusted spot colorpercentages used to obtain desired target thicknesses.

DETAILED DESCRIPTION

The embodiments provide a method and apparatus for printingthree-dimensional structures (also referred to as three-dimensionalstructural components, 3D structures, etc.) onto a base (e.g., anarticle such as a part of an upper in an article of footwear, a textilelayer, or other structure). The method may include receiving imageinformation at a printing system. The image information can includeinformation about a greyscale image, or more broadly a monochromaticimage, that includes pixels of various shade levels between two colors(e.g., grey shade levels between black and white for a greyscale image).Using this information, a processing system of the printing system maygenerate instructions for a printing device that allow the printingdevice to print a 3D structure onto a base according to the shade levelsof the pixels in the greyscale (or monochromatic) image. In some cases,the processing system can provide instructions in the form of a specificshade level for a given color (e.g., 50% black) to be printed from adesignated reservoir that is known by the processing system to include astructural print material. The system can receive both greyscale imagesand color images. In some cases, color images may be used to print 2Dcolor layers under and/or above a 3D structure that has been printedaccording to the greyscale image.

It may be appreciated that the embodiments are not limited to use withgreyscale images for printing 3D structures. The methods describedherein could be used with any 2D monochromatic file, which includes asingle value, or sample, for each pixel. Thus, for example, amonochromatic image file with shades or hues of red could also be usedas the basis for printing a 3D structure having greater height in darker(red) regions. As used in this detailed description and in the claims,therefore, monochromatic image is used to designate both greyscaleimages and images with hues or shades of only a single color (e.g., red,blue, etc.).

Other systems, methods, features, and advantages of the embodiments willbe, or will become, apparent to one of ordinary skill in the art uponexamination of the following figures and detailed description. It isintended that all such additional systems, methods, features, andadvantages be included within this description, be within the scope ofthe embodiments, and be protected by the following claims.

FIG. 1 is a schematic view of an embodiment of three-dimensionalprinting system 100, also referred to simply as printing system 100.Some embodiments of the printing system can include provisions thatdistribute one or more functions among different devices of the printingsystem. As shown, printing system 100 may include printing device 102,computing system 104, and network 106. In other embodiments, theprinting system may be a single device or component (not shown).

As used herein, the terms “printer,” “plotter,” “three-dimensionalprinter,” or “three-dimensional printing system” may refer to any typeof system that can print multiple layers onto a substrate, a fabric, anarticle of footwear, an article of apparel, or other article. In oneembodiment, printing device 102 could be a sign and graphics printer.

Printing system 100 may utilize various types of printing techniques.These can include, but are not limited to, toner-based printing, liquidinkjet printing, solid ink printing, dye-sublimation printing, inklessprinting (including thermal printing and UV printing),MicroElectroMechanical Systems (MEMS) jet printing technologies as wellas any other methods of printing.

Some embodiments may use additive manufacturing techniques orthree-dimensional printing techniques. Three-dimensional printing, or“3D printing,” comprises various technologies that may be used to formthree-dimensional objects by depositing successive layers of material ontop of one another. Exemplary 3D printing technologies that could beused include, but are not limited to, fused filament fabrication (FFF),electron beam freeform fabrication (EBF), direct metal laser sintering(DMLS), electron beam melting (EMB), selective laser melting (SLM),selective heat sintering (SHS), selective laser sintering (SLS),plaster-based 3D printing (PP), laminated object manufacturing (LOM),stereolithography (SLA), digital light processing (DLP) as well asvarious other kinds of 3D printing or additive manufacturingtechnologies known in the art. Structures formed from three-dimensionalprinting systems can be used with objects formed by other manufacturingtechniques. These include textile materials used in various articles offootwear, articles of apparel, and/or protective articles.

Some of the exemplary embodiments depict printing three-dimensionalstructures onto an article (e.g., an upper for footwear); however, otherembodiments may utilize the principles discussed herein for printing andcuring print material for any application. In some other embodiments,for example, the principles discussed herein could be used to print andcure thin films or layers of print material, such as may be used inprinting a graphic or indicia onto a substrate. As used in this detaileddescription and in the claims, the term “printable feature” refers toany layer, portion, or structure formed by printing (e.g., ejection froma nozzle). In some cases, a printable feature may be one or more layersof ink, as may be deposited by a conventional inkjet printer. In othercases, a printable feature could be a 3D structural feature that hasbeen printed onto a substrate using a structural print material, such asthermoplastic materials.

In some cases, printing system 100 may make use of a combination of twoor more different printing techniques. For example, in some embodiments,coloring inks may be printed as thin layers while clear or opaque printmaterials may be printed to form structural layers of a printed objector form. The type of printing technique used may vary according tofactors including, but not limited to, material of the target article,size, and/or geometry of the target article, desired properties of theprinted image (such as durability, color, ink density, etc.) as well asprinting speed, printing costs, and maintenance requirements.

Additive manufacturing processes may be used to form structures on flatreceiving surfaces as well as on contoured or non-flat surfaces. Forexample, some embodiments depicted in the figures may illustrate methodswhereby material is printed onto a flattened surface of an article, suchas a material section of an upper that has a flat or unassembledconfiguration. In such cases, printing material onto the surface may beaccomplished by depositing material in thin layers that are also flat.Thus, a printhead or nozzle may move in one or more horizontaldirections to apply an Nth layer of material and then move in thevertical direction to begin forming the N+1 layer. However, it should beunderstood that in other embodiments, material could be printed onto acontoured or non-flat surface. For example, material could be printedonto a three-dimensional last, where the surface of the last is notflat. In such cases, the printed layers applied to the surface may alsobe contoured. In order to accomplish this method of printing, aprinthead or nozzle may be configured to move along a contoured surfaceand tilt, rotate, or otherwise move so that the printhead or nozzle isalways aligned approximately normal to the surface where printedmaterial is being applied. In some cases, a printhead could be mountedto a robotic arm, such as an articulated robotic arm with 6 degrees offreedom.

Alternatively, in still other embodiments, an object with a contouredsurface could be reoriented under a nozzle so that contoured layers ofprinted material could be applied to the object. For example,embodiments could make use of any of the systems, features, components,and/or methods disclosed in Mozeika et al., U.S. Patent PublicationNumber 2013/0015596, published Jan. 17, 2013 (and filed as U.S.application Ser. No. 13/530,664 on Jun. 22, 2012), titled “Roboticfabricator,” the entirety of which is herein incorporated by reference.Embodiments could also make use of any of the systems, features,components, and/or methods disclosed in Cannell et al., U.S. Pat. No.8,123,350, issued Feb. 28, 2012, titled “Computerized apparatus andmethod for applying graphics to surfaces,” the entirety of which isherein incorporated by reference. Thus, it may be appreciated that thepresent embodiments are not limited to printing processes used forprinting to flat surfaces and may be used in conjunction with printingsystems that can print to any kinds of surfaces having any kinds ofgeometry.

Generally, embodiments could apply any kind of print material to asubstrate. As used herein, the term “print material,” “printingmaterial,” or “printable material” refers to any material that can beprinted, ejected, emitted, or otherwise deposited during an additivemanufacturing process. Exemplary print materials include inks as well asresins, plastics, or other print materials associated with 2D and/or 3Dprinting. In some embodiments, the materials used in the printingtechnology could be any aqueous ink, dye-based ink, pigment-based ink,solvent-based ink, dye-sublimation ink, thermoplastics (e.g., PLA andABS) and thermoplastic powders, acrylic resin, polyurethane,thermoplastic polyurethane, silicone, or any other curable substance.Still further examples of materials include high-density polyurethylene,eutectic metals, rubber, modeling clay, plasticine, RTV silicone,porcelain, metal clay, ceramic materials, plaster, and photopolymers, aswell as possibly other materials known for use in 3D printing.

In some embodiments, a print material may be any material that issubstantially moldable and/or pliable above a predetermined temperature,such as a glass-transition temperature and/or a melting temperature. Inone embodiment, a print material has one or more thermal properties suchas a glass-liquid transition (“glass transition”) temperature and/or amelting temperature. For example, the print material may be athermoplastic material having a glass-transition temperature and amelting temperature. As used herein, thermoplastic materials mayinclude, for example, acrylic, nylon, polybenzimidazole, polyethylene,polypropylene, polystyrene, polyvinyl chloride, polytetrafluoroethylene(PTFE), and the like.

In some embodiments, a print material may be UV curable. Generally, anyappropriate type of UV-curable print material, including acrylic resin,polyurethane, TPU, silicone, or any other appropriate print materialcould be used.

Some embodiments of the printing system can include provisions thatpermit printed structures to be printed directly onto one or morearticles. The term “articles” is intended to include both articles offootwear (e.g., shoes) and articles of apparel (e.g., shirts, pants,etc.). As used throughout this disclosure, the terms “article offootwear” and “footwear” include any footwear and any materialsassociated with footwear, including an upper, and may also be applied toa variety of athletic footwear types, including baseball shoes,basketball shoes, cross-training shoes, cycling shoes, football shoes,tennis shoes, soccer shoes, and hiking boots, for example. As usedherein, the terms “article of footwear” and “footwear” also includefootwear types that are generally considered to be nonathletic, formal,or decorative, including dress shoes, loafers, sandals, slippers, boatshoes, and work boots.

While the disclosed embodiments are described in the context of articlesof footwear, various embodiments may further be equally applied to anyarticle of clothing, apparel, or equipment that includesthree-dimensional printing. For example, various embodiments may beapplied to hats, caps, shirts, jerseys, jackets, socks, shorts, pants,undergarments, athletic support garments, gloves, wrist/arm bands,sleeves, headbands, any knit material, any woven material, any nonwovenmaterial, sports equipment, etc. Thus, as used herein, the term “articleof apparel” may refer to any apparel or clothing, including any articleof footwear, as well as hats, caps, shirts, jerseys, jackets, socks,shorts, pants, undergarments, athletic support garments, gloves,wrist/arm bands, sleeves, headbands, any knit material, any wovenmaterial, any nonwoven material, and the like.

In order to apply printed materials directly to one or more articles,printing device 102 may be capable of printing onto the surfaces ofvarious kinds of materials. Specifically, in some cases, printing device102 may be capable of printing onto the surfaces of various materialssuch as a textile, natural fabric, synthetic fabric, knit, wovenmaterial, nonwoven material, mesh, leather, synthetic leather, polymer,rubber, and foam, or any combination of them, without the need for arelease layer interposed between a substrate and the bottom of theprinted material, and without the need for a perfectly or near-perfectlyflat substrate surface on which to print. For example, the disclosedmethods may include printing a resin, acrylic, thermoplastic material,or ink material onto a fabric, for example, a knit material, where thematerial is adhered/bonded to the fabric and where the material does notgenerally delaminate when flexed, rolled, worked, or subject toadditional assembly processes/steps. As used throughout this disclosure,the term “fabric” may be used to refer generally to materials chosenfrom any textile, natural fabric, synthetic fabric, knit, wovenmaterial, nonwoven material, mesh, leather, synthetic leather, polymers,rubbers, and foam. As used throughout this disclosure, the term “base”or “base element” may refer to any piece of fabric, textile, or othermaterial that may comprise some or all of an article, such as a layer offabric that is used in forming an upper.

In some embodiments, printing system 100 can include provisions thatcontrol and/or receive information from printing device 102. Theseprovisions can include computing system 104 and network 106. Generally,the term “computing system” refers to the computing resources of asingle computer, a portion of the computing resources of a singlecomputer, and/or two or more computers in communication with oneanother. Any of these resources can be operated by one or more humanusers. In some embodiments, computing system 104 may include one or moreservers. In some embodiments, a print server may be primarilyresponsible for controlling and/or communicating with printing device102, while a separate computer (e.g., desktop, laptop, or tablet) mayfacilitate interactions with a user. Computing system 104 can alsoinclude one or more storage devices including, but not limited to,magnetic, optical, magneto-optical, and/or memory, including volatilememory and non-volatile memory.

In those instances where a computing system is used, any suitablehardware or hardware systems may be used to facilitate provisions thatcontrol and/or receive information from printing device 102. In someembodiments, where a computing system is used, computing system 104 mayinclude central processing device 115, viewing interface 116 (e.g., amonitor or screen), input devices 117 (e.g., keyboard and mouse), andsoftware for designing a computer-aided design representation of aprinted structure. However, in other embodiments, other forms ofhardware systems may be used.

In those instances where software for designing a computer-aided designrepresentation of a printed structure is used, any suitable informationmay be used to facilitate provisions for designing a computer-aideddesign representation of a printed structure. In at least someembodiments, the computer-aided design representation of a printed layerand/or printed structure may include not only information about thegeometry of the structure but also information related to the materialsrequired to print various portions of the structure. However, in otherembodiments, different information may be used.

In those instances where software for designing a computer-aided designrepresentation of a printed structure is used, any suitable designstructure may be used to transform the design into information that canbe interpreted by printing device 102 (or a related print server incommunication with printing device 102). In some embodiments, printingsystem 100 may be operated as follows to provide one or more structuresthat have been formed using a three-dimensional printing, or additiveprocess. Computing system 104 may be used to design a structure. Thismay be accomplished using some type of CAD software, or other kind ofsoftware. The design may then be transformed into information that canbe interpreted by printing device 102 (or a related print server incommunication with printing device 102). In some embodiments, the designmay be converted to a three-dimensional printable file, such as astereolithography file (STL file); in other cases, the design may beconverted into a different design structure. In still other embodiments,information about a structure to be printed may be sent in the form ofan image file in which case image information (colors, hues, shades,transparency, etc.) of different regions can be used to determine acorresponding 3D structure. In some embodiments, for example, a designmay include a greyscale image that includes pixels of varying shadelevels between white and black.

In those instances where a network is used, network 106 may use anywired or wireless provisions that facilitate the exchange of informationbetween computing system 104 and printing device 102. In someembodiments, network 106 may further include various components such asnetwork interface controllers, repeaters, hubs, bridges, switches,routers, modems, and firewalls. In some embodiments, network 106 may bea wireless network that facilitates wireless communication between twoor more systems, devices, and/or components of printing system 100.Examples of wireless networks include, but are not limited to, wirelesspersonal area networks (including, for example, Bluetooth), wirelesslocal area networks (including networks utilizing the IEEE 802.11 WLANstandards), wireless mesh networks, mobile device networks as well asother kinds of wireless networks. In other cases, network 106 could be awired network including networks whose signals are facilitated bytwister pair wires, coaxial cables, and optical fibers. In still othercases, a combination of wired and wireless networks and/or connectionscould be used.

As discussed, a printing system may distribute various functionalityacross one or more devices or systems. In those instances where theprinting system includes provisions that distribute one or morefunctions among different devices of printing system 100, any suitableprotocol, format, and method may be used to facilitate communicationamong the devices of printing system 100. In some embodiments, thesecommunications are conducted using network 106; in other cases, thesecommunications may be conducted directly between devices of printingsystem 100.

Printing device 102 may include a receiving surface, or printingsurface, where an article, or more generally a base, or base element(textile, etc.), can be placed for printing. In FIG. 1 , printing device102 includes a table-like structure with printing surface 103 where abase, such as a part of an article, can be placed for printing.Additionally, printing device 102 may include print head assembly 400that further includes at least one reservoir of a structural printmaterial that can be printed onto a base.

FIG. 2 is a schematic overview of inputs and outputs to printing system100, according to an embodiment. Referring to FIG. 2 , image file 200may be sent to printing system 100. In some cases, image file 200 may bestored on the same computing system that is part of printing system 100(e.g., computing system 104). In other embodiments, image file 200 couldbe stored on a different system or device from printing system 100.Moreover, image file 200 could be generated by any computer system ordevice (e.g., a digital camera) and/or processed with any processingsoftware (e.g., Adobe Photoshop) or hardware.

As used herein, an image file may be any kind of file that includesinformation corresponding to one or more images. Generally, any kind ofimage file format could be used, including, but not limited to, JPG,PNG, GIF, TIF, RAW, as well as various other kinds of image file formatsincluding formats specific to 2D or 3D printing (e.g., STL). Moreover,it may be understood that an image file could include header informationor any other additional information beyond information that directlycorresponds to an image.

In the embodiment of FIG. 2 , image file 200 comprises informationrelated to a single image 202, which is depicted schematically on thescreen of computing system 104. Here, image 202 is intended to berepresentative of a greyscale image, which uses only black, white, andgrey shading. In contrast, other embodiments could include one or morecolor images, as discussed in further detail in the embodiment shown inFIGS. 8-10 .

Using information from image file 200, printing system 100 may produceupper 204 with printed components 206. Specifically, printing device 102prints structural print material 299 (using print head assembly 400)onto upper 204 to form printed components 206. In the exemplaryembodiment, printed components 206 include eyelet elements 216 as wellas geometric printed feature 208 in toe region 210 of upper 204. Here,eyelet elements 216 are represented in image 202 with pixels 209 havinga dark grey (i.e., 70% black) shade level. In contrast, geometricprinted feature 208 includes regions of varying heights corresponding todifferent pixel colors in image 202. For example, thinner region 230 ofgeometric printed feature 208 corresponds with a section of pixels 205in image 202 having a light grey shade level. Likewise, thicker region232 of geometric printed feature 208 corresponds with a section ofpixels 207 in image 202 having a darker grey shade level. In some cases,using smoothly varying shade levels in a greyscale image allows for thecreation of generally smooth 3D contours in the resulting printedstructure.

Thus, the embodiments include provisions for printing 3D structures ontoan article using information from 2D images. This is accomplished, inpart, by instructing a printing device to deposit more print material inregions where a 2D image is darker and instructing a printing device todeposit less print material in regions where a 2D image is lighter.Moreover, as discussed in further detail below, the printing device isinstructed to print from a reservoir containing a structural printmaterial, rather than an ink or other conventional print material forforming 2D layers or images. Such a method may be used to produce 3Dprinted structures (or components) without requiring a 3D print file,such as a stereolithography (STL) formatted file.

FIG. 3 is a schematic view of some of the components and systems ofprinting system 100. Initially, information from image file 200 may besent to processing system 300, which may also be referred to as aprinting control system. Processing system 300 may provide a set ofprinting instructions to printing device 102. Specifically, processingsystem may include any systems, components, methods, or processesrelated to generating printing instructions for producing 3D structuresfrom 2D image information and/or from 3D printing files. In someembodiments, processing system 300 converts image information in imagefile 200 into information about which colors should be printed at eachprint location, or pixel, along the print surface (e.g., the surface ofan upper or other article). Thus, for example, processing system 300 mayconvert RGB (and possible hue, saturation, and brightness) values foreach pixel of the image into specific ink colors (including combinationsof ink colors) to be printed at a location corresponding to that pixel.In some cases, processing system 300 could further determine a shadelevel (e.g., 40% black) or quantity of each ink to be printed. Forexample, to print absolute black on a particular location of asubstrate, processing system 300 may send information that instructsprinting device 102 to print a maximum amount of ink (which is preset)at the given location, while to print grey on another location of thesubstrate, processing system 300 may send information that instructsprinting device 102 to print 50% of the maximum amount of ink at theother location. When non-structural print materials such as inks areused, the use of additional ink at a given location may create a fulleror richer color. However, when structural print materials are used,additional material may result in the buildup of 3D structures on thesurface of the substrate. As discussed in more detail below, processingsystem 300 may send information to printing device 102 that specifieswhich cartridge, reservoir, or nozzle that print material for aparticular “color” should be printed from.

FIG. 4 illustrates a schematic view of an enlarged portion of a printhead assembly 400 of printing device 102. In some embodiments, printhead assembly 400 may be further mounted to an actuating system of somekind. In some cases, an actuating system (not shown) may include variousprovisions for facilitating the movement of print head assembly 400and/or other components or devices. It may be understood that any knownsystems, devices, or methods for moving printheads to various positionswithin a printer or similar device could be used. Such provisions mayinclude various kinds of electric motors, or other drive devices knownin the art for use in printers.

Some embodiments of the printing device can include provisions thatpermit color printing. In some embodiments, the printing system may useCMYK printing. In other embodiments, the color printing may be conductedusing another suitable printing method.

In those instances where CMYK printing is used, any suitable device,protocol, standard, and method may be used to facilitate the colorprinting. As used herein, “CMYK” may refer to four pigments used incolor printing: “C” for a cyan pigment, “M” for a magenta pigment, “Y”for a yellow pigment, and “K” for a black pigment. An example of aprinting device using CMYK printing is disclosed in Miller, U.S. PatentPublication Number 2015-0002567, published on Jan. 1, 2015, titled“Additive Color Printing” (U.S. patent application Ser. No. 13/927,551,filed on Jun. 26, 2013), which application is herein incorporated byreference and referred to hereafter as the “Color Printing” application.In some embodiments, the printing system 100 can include one or morefeatures of the systems, components, devices, and methods disclosed inthe Color Printing application to facilitate color printing. Forexample, printing device 102 may be configured to print an image bydispensing droplets of a print material including one or more pigmentsonto a base. As used herein, droplets may refer to any suitable volumeof print material. For example, a droplet may be 1 milliliter of printmaterial. In other embodiments, printing system 100 may use othersystems, components, devices, and methods.

In those instances where CMYK printing is used, CMYK may produce orapproximate any color in the visible spectrum by printing andintermixing various combinations of pigments. Referring to FIG. 4 ,print head assembly 400 includes separate ink cartridges for cyan (C),magenta (M) and yellow (Y). Thus, the printhead assembly can dispenseinks or other colored print materials for the colors cyan (dispensed bynozzle 232), magenta (dispensed by nozzle 234), and yellow (dispensed bynozzle 236). Combinations of the dispensed colored materials may beintermixed to produce one or more colors of red, green, and blue.Further intermixing of colored print materials may be used to producemany more colors beyond red, green, blue, cyan, magenta, and yellow. Inthe exemplary embodiment, print head assembly 400 may further include aseparate cartridge for dispensing black ink or black print material (K),which may be dispensed by nozzle 238. In some embodiments, printingdevice 102 may include a white cartridge for dispensing white printmaterial (W), which may be dispensed by nozzle 239. While one cartridgefor each print material is depicted in FIG. 4 , consistent with someembodiments, printing device 102 may include more than one cartridge forone or more of the print materials of print head assembly 400. Forpurposes of convenience, the terms “nozzle,” “reservoir,” and“cartridge” may be used interchangeably in the specification and claimsto refer to the source of a particular type of print material (includinginks and structural print materials). It may be appreciated, however,that in some cases multiple nozzles could dispense ink from a commonreservoir or cartridge of print material.

In those instances where CMYK printing is used, any suitable printmaterial may be used to facilitate color printing. In some embodiments,CMYK print materials may be water based. In other embodiments, CMYKprint materials may be oil based. In some embodiments, CMYK printmaterial may include a structural print material.

Some embodiments may also use a structural print material, whose purposeis to provide 3D structure rather than color. In some embodiments, CMYKprint materials may include a clear and/or transparent structure printmaterial. In some embodiments, a CMYK print material may include anopaque structure print material. In some embodiments, the CMYK printmaterial may include a translucent structure print material. In otherembodiments, the structural material may have a combination oftransparent structural material and/or translucent structural material.

Referring to FIG. 4 , print head assembly 400 includes at least onecartridge that dispenses a clear structural print material (CL), whichis dispensed by nozzle 240. Although the exemplary embodiments may useclear structural print materials, other embodiments could includestructural print materials with pigments.

Although not shown in the figures, embodiments that incorporatestructural print materials can include curing devices to help cure theprint materials. Embodiments may include provisions for curing one ormore kinds of print materials. Generally, any known methods and/ordevices for curing printable substances could be used. Some embodimentsmay use ultraviolet (UV) curing lamps. Embodiments using a UV lamp canutilize any type of UV lamp. Exemplary lamps that could be used with theembodiments include, but are not limited to, mercury vapor lamps(including H type, D type, or V type mercury lamps), fluorescent lamps,and/or UV LED devices. The type of lamp used may vary according to thetype of print material, the type of printing application, the type ofprinting device used, as well as other manufacturing considerationsincluding cost and availability. Other embodiments could use other formsof curing, such as electron-beam curing. Still other embodiments couldomit curing devices.

As previously discussed, it is contemplated that a printing system couldprint a 2D image to form a 3D structure by instructing a printing deviceto print various shade levels of a print material from a designatedcartridge having a structural print material. In some cases, printingsimilar quantities of a structural print material rather than aconventional ink may result in regions of different thickness or heightin a 3D printed component.

FIG. 5 is a schematic view of the relationship between the shade levelof a region of an image (e.g., a pixel) and the corresponding amount ofstructural print material that would be deposited in the correspondingregion on a base. In a greyscale image, each pixel may take on anycolors or shades between “solid white” and “solid black”, which arehereby referred to as “shade levels.” In situations where a colored ink(e.g., black) is used to print a greyscale image, the printing systemmay instruct the printer to deliver different volumes of ink atlocations corresponding to pixels having different shade levels. Forexample, printing a greyscale image with black ink may include printinga maximum predetermined volume or quantity of ink for solid blackpixels, printing no ink for solid white pixels and printing some rangeof volume between zero volume and the maximum predetermined volume forpixels of intermediate shade levels.

As seen in FIG. 5 , in some embodiments the printing instructions forprinting different shade levels could be used to print structural layersof different heights, since each shade level corresponds with adifferent volume of print material. For example, locations on a printsurface corresponding to regions or pixels of an image with solid whiteshade level 502 would not receive any print material. In contrast,locations on a print surface corresponding to regions or pixels of animage with solid black shade level 510 would receive a maximumpredetermined volume of print material. At these locations, thestructural print material may be formed into a portion with height 528.Further, locations on a print surface corresponding to regions or pixelsof an image having intermediate shade levels between solid white andsolid black would receive a corresponding percentage of the maximumpredetermined volume of print material. For example, light grey shadelevel 504 that is slightly darker than solid white shade level 502 mightreceive 25% of the total volume of a structural print material,resulting in a structure with height 522, which may be 25% of height528. Similarly, medium grey shade level 506 might receive 50% of thetotal volume of a structural print material, resulting in a structurewith height 524, which may be 50% of height 528. Further, dark greyshade level 508 might receive 75% of the total volume of a structuralprint material, resulting in a structure with height 526, which may be75% of height 528. Therefore, it may be seen that a 3D structural objectcan be formed by using shade level information to print varying volumesof print material on a print surface. In some cases, the relationshipbetween the height of a printed region and a shade level may be linear.For example, in some cases as the shade level is doubled (e.g., from 20%black to 40% black) the height is doubled (e.g., from two printed layersto four printed layers).

It may be appreciated that the structures shown in FIG. 5 could beformed with a single pass of a printhead in which the volume of printmaterial is varied at each location. Alternatively, in otherembodiments, these structures could be successively built up by printinga single layer of fixed height for each pass of the printhead, andapplying more layers to taller regions. It may be further appreciatedthat both methods may be accomplished by providing different shadelevels to a printing device, as the device may be configured to printdifferent shade levels with standard inks using a single pass or bysuccessively applying more ink to certain pixels with multiple passes.

FIG. 6 is an embodiment of a schematic method of operation of a printingsystem. It may be appreciated that some of the following steps could beoptional in some embodiments. Other embodiments could include additionalsteps not shown in FIG. 6 . Moreover, in some embodiments, the varioussteps described here could be accomplished by a printing system,including a subsystem of a printing system (such as a processing systemor a printing device). In other embodiments, one or more steps could beaccomplished by any other system peripheral to the printing system.

For purposes of understanding the following process, an exemplaryconfiguration of a printing system utilizing this process is shown inFIG. 7 and discussed in reference to the process of FIG. 6 .

In step 602, a printing system may receive an image file withinformation corresponding to a greyscale image. For example, in somecases a user may import an image file from a file location on acomputing system associated with the printing system. In some cases, theimage file may be created and/or modified using graphical software, suchas image editing software. In some cases, this software may beconsidered part of the printing system, while in other cases thissoftware could be considered as external to the system. FIG. 7 depictsexemplary 2D image 702 that is received at processing system 300.

Next, in step 604, the printing system may retrieve information aboutthe nozzles and corresponding print materials for each nozzle associatedwith one or more printheads of the printing device. Specifically, insome cases, the printing system may determine which print nozzles havecolor inks, including which nozzles have black ink, as well as whichnozzles may have structural print materials. In some cases, thisinformation can be stored in a database of the printing system prior toprinting. In other cases, the printing system could prompt a user toprovide this information. In some cases, the information may be providedas identification information for one or more reservoirs of printmaterials (for one or more nozzles or cartridges). Thus, for example, inan embodiment where different reservoirs are identified using some IDnumber, the printing system may determine the ID numbers correspondingto reservoirs with structural print material.

It may be appreciated that in some cases a printing device may not haveinformation about the type of print material in each print cartridge. Inprinters that are modified to print structural print material, forexample, the structural print material may be disposed in a reservoirthat is usually intended to hold a colored ink. Therefore, the printinginstructions submitted to the printing device by, for example, aprocessing system, may include ID information about each nozzle withexplicit instructions about which nozzle to use for printing. Thus, whenthe system prints a 2D greyscale image as a flat 2D layer, the printingdevice may be instructed to print from a nozzle that contains black ink,and when the system prints 3D structure, the printing device may beinstructed to print from a nozzle that contains a structural printmaterial. In either case, the printing device provides a given volume ofprint material according to the target shade level.

As an example of step 604, the embodiment shown in FIG. 7 includesreservoir information 704 that is also received at processing system300. Specifically, reservoir information 704 indicates that reservoir #5of a printhead assembly 710 in printing device 102 includes a clearstructural print material. Thus, for purposes of illustration,processing system 300 is seen to have knowledge of the print material ineach of the reservoirs of an exemplary print head (represented in FIG. 7in internal processes).

During step 606, the printing system provides instructions to theprinting device to print the image file information using a set ofnozzles with structural print material. In some cases, during step 606,the printing system provides instructions including the ID of areservoir to print from, as well as a color and/or shade level, such as50% black. As indicated in FIG. 7 , print device 102 operates as thoughreservoir #5 includes a black ink, which may include calculating anamount of print material to deposit at each location based on agreyscale shade level.

In FIG. 7 , exemplary set of print instructions 706 are illustrated. Inthis example, exemplary set of print instructions 706 includeinstructions for printing a particular shade level at given locations(e.g., “x1, y1”, “x1, y2”, etc.). In some cases, the shade level may begiven as a percent of an absolute color (e.g., “30% black,” “35% black,”etc.). Additionally, exemplary set of print instructions 706 may specifythe location of the reservoir that contains the instructed ink color. Inthis case, when the printing device prints from the instructedreservoir, a structural print material is deposited rather than a blackink, which forms a resulting 3D structure.

This configuration may allow a printing device to print 3D structureswithout requiring the printing device to have provisions for using 3Dprint files or 3D print drivers. Instead, 3D printing is accomplished byproviding the printing device with instructions expected for printed 2Dimages, but using a structural print material that allows for thecreation of 3D contours.

Some embodiments may include provisions that allow a printing system toknow when a greyscale image should be printed as a 2D greyscale designvs. using the image information to print a 3D structure. In some cases,the printing system may determine if the image file information isintended to be used for 3D printing prior to instructing a printingdevice. In other words, the printing system (i.e., processing system 300of FIG. 3 ) determines if the image file information should be used forprinting a 3D structure. In different embodiments, the system may makethis determination in a number of different ways. In some cases, a userof the system provides an explicit instruction to the system, such asthrough a GUI or command line interface with the printing system, whichinforms the system that the image file information should be used inprinting a 3D structure. In other cases, a printing system can havecapabilities for automatically determining that a given file is intendedto be used for printing a 3D structure. In some cases, for example, theimage file could include header information or other metadata thatindicates its intention for use in 3D printing.

FIG. 8-9 illustrate schematic views of another embodiment for printingsystem 800. The embodiment of FIGS. 8-9 may share many features of theprevious embodiments, and may also include some new features as well asleave out other features. For example, in FIGS. 8-9 , printing system800 is configured to receive information for three different images.These include first color image 802, greyscale image 804, and secondcolor image 806. Similarly to the previous embodiment, greyscale image804 comprises information that can be used by printing system 800 toform three-dimensional structures 810. In addition, first color image802 and second color image 806 can be applied to top surface 812 andbottom surface 814, respectively, of components 810. Moreover, secondcolor image 806 could be an inner color layer that is disposed betweencomponents 810 and underlying base 801 (i.e., an upper in thisembodiment).

The image information passed to the printing system could take onvarious forms in different embodiments. For example, in someembodiments, each image could be sent as a separate file to the printingsystem (e.g., each image could be a separate jpeg, png, tiff, or otherkind of graphics file). In FIG. 9 , for example, each image is sent as aseparate file (i.e., image file 820, image file 830, and image file840). In other embodiments, multiple images could be sent as part of asingle file. Still other embodiments may include provisions for sendingimage information with additional information, such as variousparameters, that could be provided as part of a header (e.g., as part ofthe header in a tiff file, which supports header information).

It may also be appreciated that other embodiments could use only a topcolor image or a bottom color image. In some embodiments, for example,only a bottom color image could be used and the resulting printedarticle would include a bottom color layer with an overlaid 3Dstructure. In other embodiments, only a top color image could be usedand the resulting printed article would include a 3D structure printeddirectly to the article (without an intermediate color layer) and wouldalso include a top color layer printed onto the structure.

FIG. 10 is an embodiment of a schematic method of operation of aprinting system. It may be appreciated that some of the following stepscould be optional in some embodiments. Other embodiments could includeadditional steps not shown in FIG. 10 . Moreover, in some embodiments,the various steps described here could be accomplished by a printingsystem, including a subsystem of a printing system (such as a processingsystem or a printing device). In other embodiments, one or more stepscould be accomplished by any other system peripheral to the printingsystem.

In step 1002, a printing system may receive image file information. Forexample, in some cases, a user may import an image file from a filelocation on a computing system associated with the printing system. Insome cases, the image file may be created and/or modified usinggraphical software, such as image editing software. In some cases, thissoftware may be considered part of the printing system, while in othercases this software could be considered as external to the system.

In the present embodiment, information about multiple images could bereceived. For example, information about a greyscale image as well asinformation about one, two, or more color images could also be received.In some cases, the different images could be received as separate files.In other cases, the images could be represented by data in a singlefile.

In step 1004, the printing system selects information about one of theimages. In cases where a single file may be received, the printingsystem extracts the information corresponding to one of the images inthe file. In other cases, the printing system selects a filecorresponding to an image among multiple files.

In step 1006, the printing system determines if the image is for 3Dprinting. This may be determined in various ways, including by checkinga parameter or other metadata received with the image information thatindicates the image is for 2D or 3D printing. In other cases, theprinting system could automatically determine if the image is to be usedfor 3D printing according to the image information itself. For example,in some cases a printing system is configured so that any pure greyscalefile is always assumed to be for 3D printing.

If the image is not for 3D printing, the printing system proceeds tostep 1008. The printing system will send normal printing instructionsfor printing 2D color layers (or 2D black/white layers).

However, if the system determines during step 1006 that the image isintended to be used for 3D printing, the printing system proceeds tostep 1010. The printing system may then generate and submit modifiedprinting instructions for printing a 3D structure using the imageinformation. In some embodiments, the printing system could follow stepssimilar to step 602, step 604, and step 606 of FIG. 6 in generating andsubmitting the instructions to print a 3D structure using the imageinformation.

As used throughout this detailed description and in the claims, theterms “normal printing instructions” may generally refer to instructionsgenerated and sent to a printing device when a 2D layer is printed. Incontrast, “modified print instructions” are generated and sent to aprinting device for printing a 3D object or layer. The distinctionbetween these two types of instructions can vary in differentembodiments. In one embodiment, modified print instructions includeinstructions to print from a reservoir having a structural printmaterial (clear or opaque), whereas normal print instructions includeinstructions to print from a reservoir having a “conventional printmaterial” for 2D printing, such as an ink or dye that cannot be used forforming 3D contoured structures or objects.

FIG. 11 is a schematic view of an embodiment of file 1100 for use with aprinting system. In some embodiments, file 1100 may include imageinformation as well as other parameters and/or metadata. As seen in FIG.11 , file 1100 may include image portion 1102 that contains imageinformation or image data. Additionally, file 1100 could include headerportion 1104 that contains information about metadata, such as themaximum height of a 3D structure. In some cases, header portion 1104could also indicate whether the structure should be printed with a fixedor variable number of layers. The header information can be used todetermine how many layers to print at each point or location (insituations where a variable number of layers are printed) or how thickto print the layers at each point or location (in situations where afixed number of layers are printed).

FIGS. 12-13 illustrate schematic views for an embodiment where aprinting system prints a variable number of layers of a structural printmaterial in order to achieve a particular thickness at a given locationof a structure. Specifically, FIG. 12 illustrates a schematic view oftwo printing locations for a 3D structure. At first location 1202, fourprinted layers 1204 of fixed height 1250 are printed as determined byshade level 1210 at a corresponding pixel in a greyscale file. At secondlocation 1206, only two printed layers 1204 of fixed height 1250 areprinted as determined by shade level 1212 at a corresponding pixel inthe same greyscale file. Thus, it may be clearly seen that in some casesa printing system prints portions with varying heights by stacking updifferent numbers of constant thickness layers, according to the shadelevel representing that location within a greyscale file.

FIG. 13 illustrates an embodiment of a process for printing using avariable number of layers to form three-dimensional structures. In step1302, the printing system receives the maximum height of a structure.This value may be input manually by an operator of the system or couldbe provided as data along with image information for the greyscaleimage. The maximum height may be the printed height for any region wherea corresponding pixel of the greyscale image is 100% black (or themaximum shade level). Next, in step 1304, the printing system maydetermine, or otherwise receive, the constant layer thickness. This maybe the thickness of each layer to be printed. In some cases, this valuecould be calculated or otherwise determined according to the maximumheight and using other parameters to constrain the thickness. In othercases, the constant layer thickness is given as an input to the printingsystem.

Next, in step 1306, the printing system may receive gradient data withdifferent shade levels. In some cases, the gradient data is greyscaleinformation. However, it may be appreciated that in other embodimentsgradient data could be provided as different shades of a non-grey color,such as shades of blue or shades of red. Such gradient data could betreated in a similar manner to greyscale data for the purposes offorming a 3D printed structure.

Finally, in step 1308, the printing system may determine the number oflayers to print at each location according to the shade level. Thus,regions with 100% black shade levels may be printed to have the maximumthickness or height of the 3D structure, while regions with less than100% black shade levels will have less thickness or height when printed.Moreover, using this configuration, the regions of maximum thicknesswill have a greater number of layers than the regions with thicknessesless than the maximum thickness.

FIG. 14-15 illustrate schematic views for an embodiment where a printingsystem prints a fixed number of layers (N layers) of a structural printmaterial, and where the layers may have different thicknesses, in orderto achieve a particular thickness at a given location of a structure.Specifically, FIG. 14 illustrates a schematic view of two printinglocations for a 3D structure. At first location 1402, five printedlayers 1404 of first height 1450 are printed as determined by shadelevel 1410 at a corresponding pixel in a greyscale file. At secondlocation 1406, five printed layers 1408 of second height 1452 areprinted as determined by shade level 1412 at a corresponding pixel inthe same greyscale file. Thus, it may be clearly seen that a printingsystem prints portions with varying heights by printing a constantnumber of layers, where each layer has a thickness proportional to theshade level for that location.

FIG. 15 illustrates an embodiment of a process for printing using afixed number of layers at each location and varying the thickness ofthose layers to form three-dimensional structures. In step 1502, theprinting system receives the maximum height of a structure. This valuemay be input manually by an operator of the system or could be providedas data along with image information for the greyscale image. Next, instep 1504, the printing system may determine, or otherwise receive, thefixed number of layers. In some cases, this value could be calculated orotherwise determined according to the maximum height and using otherparameters to constrain the thickness. In other cases, the fixed numberof layers is given as an input to the printing system.

Next, in step 1506, the printing system may receive gradient data withdifferent shade levels. In some cases, the gradient data is greyscaleinformation. However, it may be appreciated that in other embodimentsgradient data could be provided as different shades of a non-grey color,such as shades of blue or shades of red. Such gradient data could betreated in a similar manner to greyscale data for the purposes offorming a 3D printed structure.

Finally, in step 1508, the printing system may determine the number oflayers to print at each location according to the shade level. Thus,regions with 100% black shade levels may be printed to have the maximumthickness or height of the 3D structure, while regions with less than100% black shade levels will have less thickness or height when printed.Moreover, this is accomplished by printing each layer with a firstthickness in darker regions and each layer with a second thickness thatis less than the first thickness in lighter regions.

Some embodiments can include provisions for increasing the precision ofprinting smooth contoured 3D surfaces. In some embodiments, a printingsystem can include provisions for correlating a spot color percentagefor a given ink with a desired ink layer height. Here, the term ‘spotcolor’ may refer to the use of a standardized ink or print material forwhich various properties (such as color density for a given quantity ofink) are known. In other words, a spot color may also be referred to asa standardized color. In the context discussed in the followingembodiment, ‘spot color’ can refer to clear structural inks as well. Insome cases, a known greyscale spot color range (0-100%) may be used fora clear structural ink. However, instead of using variations in spotcolor percentage to control color density in a layer, the print systemmay use spot color to control the thickness of one or more structurallayers.

FIG. 16 illustrates a schematic relationship between a clear (CLR) spotcolor percentage for a given clear structural ink (columns 1602), and aresulting print layer thickness (column 1604). If provided with the datacontained in such a table, a print system can print layers of a widerange of thicknesses by selecting the associated spot color percentagefor printing to achieve the desired thickness (alternatively a designerand/or graphics program can provide data with the desired spot colorpercentages to a printing system to achieved desired thicknesses in theresulting printed object). This may allow for the creation of verysmooth contours and height gradients as the print system has very fineand precise control over layer thicknesses.

For example, FIGS. 17 and 18 illustrate two schematic views ofembodiments of printed structures with smoothly varying heights thathave been achieved by printing layers according to gradually varyingcolor percentages. In FIG. 17 , printed object 1702 has a position 1703with a maximum height 1704 that corresponds with printing using a 100%spot color designated for the clear structural ink. A position 1705 justadjacent position 1703 has a height that is very slightly less thanmaximum height 1704 by printing using 99.5% spot color. In FIG. 18 , aprinted object 1802 has a position 1803 with maximum height 1804 that istwice the maximum height 1704 of FIG. 17 . To achieve this thickness,two layers of 100% spot color are printed at position 1803.

In the embodiments of FIGS. 16-18 , the corresponding print layerthicknesses are linear in the spot color percentage. In someapplications, depending on the type of ink used and/or other propertiesof the printing system, the print layer thickness may not be linear inthe spot color percentage. This may occur because the amount of inkrequired to linearly vary the color density (which determines the spotcolor percentages) may result in non-linear variations in height orthickness of printed ink layers. In order to allow a designer to createsmoothly varying contours that change in small and regular intervals(layer heights), it may be desirable to find a modified set of spotcolor percentage values that correspond with a set of regularly spacedthicknesses.

FIG. 19 illustrates a process for finding a modified (or ‘linearized’)set of spot color percentages that yield regularly spaced layerthicknesses. At least some of the following steps may be performed by anoperator of the printing system, or other system technician. In somecases, one or more of the steps can be performed by the printing systemand/or by a separate computing system.

In step 1902, an operator may print a range of spot color percentages todifferent regions of a substrate. For example, the operator could print20 spots of ink corresponding to regularly increasing spot colorpercentages (e.g., 5%, 10%, 15%, etc.). Next, in step 1904, the operatormay measure the thicknesses of each region containing ink applied usinga different spot color percentage. Exemplary tools and techniques formaking such precision measurements can include, but are not limited to:magnetic pull-off gauges, eddy current techniques, ultrasonic techniquesas well as other tools and techniques known in the art.

Next, in step 1906, the operator may compare the measured thicknesses tothe predetermined target thicknesses, for example using a spreadsheet.In some cases, the predetermined target thickness may be determinedaccording to the assumption that the thickness would vary linearly inheight as a function of spot color percentage. In step 1908, theoperator may generate a corrected table of spot color percentages forachieving the predetermined target thicknesses (e.g., using aspreadsheet).

Finally, in step 1910, the operator may make sure the corrected ormodified table is used during printing. In some embodiments, themodified table could be used on graphic data prior to sending it to theprinting system. For example, a graphics program that outputs graphicdata for use by the printing system may automatically select spot colorpercentages for printing using the modified table. In other embodiments,the modified spot color percentages could be incorporated into thesoftware of the printing system (e.g., as logic or as a look-up tablestored in a database).

FIG. 20 illustrates an example of a modified table that provides acorrelation between target thickness and an ‘adjusted spot colorpercentage’. In the left-most column 2002 of the table are regularintervals of the spot color percentage from 0 to 100 percent. In thenext two columns (column 2004 and column 2006) are the measured layerthickness and target (expected) thickness for those spot colorpercentages, respectively. Because the measured thicknesses and targetthicknesses are different the table includes a final column 2008 with anadjusted spot color percentage. It is the adjusted spot colorpercentages that should be used to achieve a desired target thickness inthe same row, rather than the spot color percentages in the first column2002. For example, using the table of FIG. 20 , in order to print alayer with a target thickness of 0.34 mm (from column 2006) the systemshould be instructed to print a 15.1% spot color (from the same row incolumn 2008).

Using the methods described herein a manufacturer can allow a designerto use spot color percentage to net a desired thickness and yield thedesired contour with a high level of accuracy. This may be accomplishedin an efficient manner by providing print instructions in terms ofpercentages of known spot colors, for which a printing system, or othersoftware, already has known data (i.e., the amount of ink or printmaterial required to achieve a desired percentage for a given spotcolor). For example, a graphics program could be configured to outputgrayscale images with given percentage of a spot color at each pixelthat will achieve a desired layer height in a 3D object that correspondswith that pixel.

While various embodiments have been described, the description isintended to be exemplary, rather than limiting, and it will be apparentto those of ordinary skill in the art that many more embodiments andimplementations are possible that are within the scope of theembodiments. Any feature of any embodiment may be used in combinationwith or substituted for any other feature or element in any otherembodiment unless specifically restricted. Accordingly, the embodimentsare not to be restricted except in light of the attached claims andtheir equivalents. Also, various modifications and changes may be madewithin the scope of the attached claims.

The invention claimed is:
 1. A method of printing a three-dimensionalstructure, comprising: receiving a file indicating a plurality ofprinted regions of a three-dimensional structure to be printed and aplurality of spot percentages of a selected spot color, with eachprinted region being associated with a spot percentage, wherein the spotpercentages are selected from a range of incremental percentages from 0%to 100%, and wherein each spot percentage corresponds to a print layerthickness for the associated printed region of the three-dimensionalstructure; successively printing a plural number of layers of structuralmaterial in the printed regions on a substrate to build up to thethree-dimensional structure, wherein each of the layers has a samethickness profile across the plurality of printed regions, the thicknessprofile of each of the layers comprising the print layer thicknesses foreach of the plurality of printed regions across the three-dimensionalstructure; wherein after the printing, a structure height for eachprinted region of the three-dimensional structure is based on the printlayer thickness for the respective printed region multiplied by thenumber of layers; wherein each of the printed regions of the printedthree-dimensional structure contains the same number of layers of thestructural material, and wherein each layer of the structural materialin a given printed region has equal thickness.
 2. The method of claim 1,further comprising printing a color layer on top of thethree-dimensional structure.
 3. The method of claim 1, wherein theselected spot color is grey or black.
 4. The method of claim 1, whereinthe spot percentages comprise even increments between 0% and 100%. 5.The method of claim 1, wherein the print layer thickness for eachprinted region varies linearly as a function of the spot percentage forthat printed region.
 6. The method of claim 1, wherein each of thelayers contains an equal amount of structural material.
 7. The method ofclaim 1, wherein the received file comprises a monochromatic imagecomprising a plurality of pixels that correspond to the plurality ofprinted regions, wherein each pixel comprises a shade of the selectedspot color, wherein the shade of each pixel corresponds to the spotpercentage for the respective printed region.
 8. The method of claim 7,wherein the thickness profile for each layer of structural material isbased on the monochromatic image.
 9. The method of claim 8, whereinprinting the three-dimensional structure comprises printing the layersof structural material based on the monochromatic image, and thenprinting a color layer on the three-dimensional structure using a colorimage.
 10. The method of claim 1, wherein each of the layers is printedwith a two-dimensional printer.
 11. The method of claim 1, whereinprinting the layers of structural material comprises printing at leastfive successive layers of structural material.
 12. The method of claim1, wherein printing the layers of structural material comprises printingat least ten successive layers of structural material.
 13. The method ofclaim 1, wherein the printed three-dimensional structure has a contouredupper surface.